Infanta Pilar of Spain, Duchess of Badajoz and Viscountess of La Torre, sometimes known more simply as Pilar de Borbón, was the elder daughter of Infante Juan, Count of Barcelona and Princess María Mercedes of the Two Sicilies, and older sister of King Juan Carlos I.

Infante Juan, Count of Barcelona, was a claimant to the Spanish throne as Juan III. He was the third son and designated heir of King Alfonso XIII of Spain and Queen Victoria Eugenie of Battenberg. His father was replaced by the Second Spanish Republic in 1931. Juan's son Juan Carlos I became king when Spain's constitutional monarchy was restored in 1975.